1. Field of the Invention
This invention relates to rectifiers and more particularly to a full wave rectifier suitable to be utilized in high speed, wide band input signal applications that can be fabricated in monolithic integrated circuit form and which exhibits excellent linearity between the output signal and the applied input signal thereto.
2. Description of the Prior Art
The prior art is replete with full wave rectifiers that are used in a myriad of applications. For instance, full wave rectifiers are commonly used in amplitude demodulation and amplitude measurement systems. Full wave rectifiers also may be utilized for video detection and are found as part of the video detector portions of television receivers to remove the video signal from the television composite carrier signal.
Some contemporary rectifiers that may be used in high speed, wide-band input signal schemes have a major problem associated therewith. In order to operate efficiently at high speeds contemporary full wave rectifiers are generally direct current biased at a quiescent operating point. As will be more fully explained later, the effect of direct current biasing causes these full wave rectifiers to have a non-linear transfer characteristic. Hence, the output signal is not an exact reproduction of the two halves of the applied alternating signal.
Another problem associated with some prior art detectors utilized, for example, as video detectors in a television set is that these detectors require a tuned circuit at the television carrier frequency. A typical example of such prior art is the Motorola Inc., MC1330 low level video detector integrated circuit which requires a tuned circuit. The tuned circuit may cause phase related problems in the television receiver as well as spurious feedback to the high sensitivity input terminals of the integrated circuit which is undesirous. Additionally, the need for a tuned circuit requires external terminals be provided between the integrated circuit and the tuned circuit which is undesirable.
Thus, a need exists for a linear full wave rectifier for operation in high speed applications and which may be utilized for example in video detection systems without the need for a tuned circuit.